Fractionating column

From theEthanolSource.com

A fractionating column is a vertically mounted pipe, typically made of copper, that is packed with a material which has air spaces in it. As the vapors rise up and hit the packing, a portion of the vapor will condense on the packing and flow back down towards the bottom. In an alcohol and water separation, the water will condense out of the vapor phase before the alcohol will. In this manner, a properly designed and cooled column will produce approximately 90% alcohol out of the top of the column. This is the highest concentration that can be produced by distillation since ethanol forms and azeotrope with the water which cannot be separated by distillation.